"zip-lock" is a trademarked name, just like Kleenex. It is also a "general" term used for a zip lock bag--a plastic bag that you "zip" to seal. Best ones to get at the kind meant for freezers, they are stronger and will hold up better in case someting explodes in the bag......

Yes, you can use a regular "zipper" bag, but as MGA said, the freezer bags that have the "plastic thingy" seal better. You don't want to be digging through your carry-on to find liquids that have "escaped" !